Advice combining blog and website from 2 different domains

I’ve been running wordpress on my main site for about a year, as well as a wordpress blog on a separate domain that’s directly related to the same content. The reason I split the two is because when I was first learning about SEO, I was told it would be a good idea to get my blog ranking, and then link to my main site constantly from the blog, which would hold more weight since they’re targeted external links, and eventually they’d even out and both rank the same. Yeah.

A year later, my blog is a PR3 with little to no effort, while my main site is only a PR1, despite busting my butt. So I obviously did it wrong.

Should I combine the two (put the blog on the main site and 301 redirect all of the blog posts to mirrored posts on the main site)? Will that waste "link juice"?

Is there something else I can do to not waste a decent PR3 blog by just shutting it down and switching to a new blog on the main site?

You'll probably get a couple of other suggestions but I think that it's better to use that PR3 site and funnel the traffic you're getting there to your main site/affiliate site. Another option is to transform your blog into an affiliate site and promote some of your products in there.

Also, while Page Rank is important, it is not everything. It is more important to drive traffic to your website/s because more traffic means more chances to make a sale. Your website's PR will also improve once you have a consistent flow of traffic on your site.